Re: Futaba Pulscale "CMC" Manual Needed

Steve:

Thanks for your feedback and insight. I don't have the machine in
my garage (yet), but I'm 99% sure these are AC servos, based on the
photos I took. If there is a way I can upload the photos for you to
take a look at??? ..... I have a clear shot of the manufacturers
label (AC Servo Motor, Type SSM-1020F, Shinko Electric Co LTD) and
good side shot (no brush caps, 2 connectors, one near the center
(windings?) one on the endcap (encoder?). Did the AC servo motors
of the '70s also use true 3-phase? This is my main question,
because if the system still works fine (have yet to see it powered
up) then I won't bother changing out the controller, as long as it
can handle some reasonable G-codes. I'll just invest in a rotary
converter and leave well enough alone.

Mike

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Steve Stallings"
<stevesng@n...> wrote:

> Are you sure the servos are AC motors? It was common with this
> vintage of equipment (1970's) to use DC motors (have brushes)

driven

> by phase angle controlled SCRs powered from 3 phase AC input. If

this

> is the case you will need real 3 phase power input. These systems

had

> really low servo bandwidth (100 Hz typical) and are prime

candidates

> for retrofit. Keep the motors, add rotary encoders to the motor,

and

> use a PWM servo amplifier that uses a DC power supply that can be
> built to operate from single phase. The encoders on the motor are
> recommended because wider bandwidth servos can difficult to tune

if

> there is any backlash between the motor and the encoder. Put a VFD

on

> the spindle if it is really an AC motor (check, many were DC in

the

> 1970's).
>
> Regards,
> Steve Stallings
> www.PMDX.com
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "m_gershowitz"
> <mgershowitz@s...> wrote:
> > Hi Folks:
> >
> > I'm hoping someone can help me out with some information on an
> older
> > CNC controller that was used on a Bridgport retrofit that I just
> > acquired (but have yet to take delivery on) for home/hobby use.
> >
> > The unit is a Futaba PulscaleCMC model PCM001 with AC servo

motors.

> >
> > I know that Futaba made DROs - this isn't one, it's a CNC
> > controller. It does use glass scales, I'm presuming to 'close

the

> > loop', but it happens that the scales on the mill
> are "Heidenhain".
> > The controller panel, servos and servo drivers are all clearly
> > Futuba labeled (although the servos are Shinko Electric, re-

labled

> > by Futaba).
> >
> > From the way it the drivers are wired it appears that 3-phase is
> > used by the servo motors.
> >
> > I'm hoping someone is familar with this setup, and maybe even

has

> > some manuals on it. I'd gladly pay the cost of repro for the
> > documentation. I haven't been able to find anything on the web.
> >
> > My understanding is that Futaba was in the CNC business in

the '70s

> > but got out of the business shortly after entering.
> >
> > I've got plenty of photos I could post if that would help ID the
> > unit. It's in great shape, and I'm told it works fine (still

need

> > to get the machine powered before I'll take delivery). My

biggest

> > concern is if I'll need true 3-phase supply (ie; rotary

converter)

> > to operate the system, or if I can get by with single phase and

a

> > VFD for the motor.
> >
> > Thanks for any insights you can provide.
> >
> > Mike G.